Copper chrome arsenate treated timber

Copper chrome arsenate (CCA) is a water-borne
solution of up to 25% copper, up to 45% chromium and up to 37% arsenic. This
treatment makes the timber highly resistant to pests and fungi but it can also
be toxic when handled or burnt, and should never be used for household building
or renovation.

Copper chrome arsenate treated logs

Copper is a fungicide, arsenic prevents insect attacks and chromium binds the other two elements to the timber. When used as a treatment, CCA makes up about 1% of the timber volume. If the timber is burnt, however, the
smoke and ash contain high concentrations of arsenic.

Existing structures containing copper chrome arsenate

The APVMA also advised that existing structures made from CCA treated timber do not need to be removed. If you are worried about children having contact with the arsenic in CCA, paint the surfaces with an oil-based polyurethane product or paint.

CCA vegetable planters can be lined with plastic.

Labelling

CCA treated timber in Australia must be marked with the words ‘Treated with copper chrome arsenate’ either in the form of individual labels fixed to the ends of wood, or as brands along its length. Some items do not need to be individually labelled, but the packaging must be marked. These include

fence palings

battens

droppers

pieces less than 15 mm thick or with a cross section below 1500 mm2

Safe handling

It is commonly believed that all green-tinged timber is CCA, but other treated timbers which do not contain arsenic may also appear green.

Because labels and brands can be removed or fade with time, identification can be difficult. If you are unsure what a treated timber structure is made from, you should play it safe and handle and dispose of it as
if it is treated with CCA.